Apparatus for making fibrous cement sheets



Sept. 27, 1955 A. MAGNAN I APPARATUS FOR MAKING FIBROUS CEMENT SHEETSFiled Jan. 18, 1952 2 Sheets-Sheet l 32 flaw 7 w liwwm ATTO R N EYSSept. 27, 1955 MAGNAN] 2,718,822

APPARATUS FOR MAKING FIBROUS CEMENT SHEETS Filed Jan. 18, 1952 2Sheets-Sheet 2 a; 64 i r INVENTOR 45m M704; EZZWW ATTORREYS United SttesPatent APPARATUS FUR MAKING FIBROUS CEMENT SHEETS Alessandro Magnani,Broni, Pavia, Italy, assignor of onehalf to F. L. Smidth & Co. A/S,Copenhagen, Denmark, a corporation of Denmark Application January 18,1952, Serial No. 267,020

Claims. (Cl. 92-38) This invention relates to the manufacture of fibrouscement sheets, and is concerned more particularly with a novel apparatusfor compressing and calendering such sheets to give them a smoothuniform surface.

Fibrous cement sheets are now commonly made by continuously feeding apasty aqueous fibrous cement material to and distributing it upon amoving endless suction support, after which the material is formed andcompressed, the excess water being drawn off through the support duringthe several operations. In the known methods, the formed material may becompressed by a rotating roller, which may be reciprocated in the planeof the layer of material, and, by rotating the roller with a surfacespeed greater than the rate of advance of the material, the layer ofmaterial may be subjected to a calendering action simultaneously withthe removal of water therefrom. Heretofore, it has been difiicult toachieve satisfactory simultaneous compression and calendering of thesheet, since it is necessary, in order to produce a smooth, closesurface on the sheet, that some water be present in the surface duringcalendering and the continuous suction eifect tends to reduce the amountof water below that required. The ditficulty referred to is enhanced asthe thickness of the sheet increases, since the dewatering of suchsheets requires stronger suction, which lessens the amount of waterpresent in the surface of the sheet.

The present invention is, accordingly, directed to the provision of anovel apparatus for simultaneously calendering and compressing formedfibrous cement sheets, which is superior to prior apparatus used for thepurpose, in that the sheets are given a smoother and more uniformsurface.

In the operation of the new apparatus, the calendering and compressingis effected by means of an element, which is caused to move relativelyto the sheet both in the plane of the sheet and at an angle to thatplane. The movement of the element in the plane of the sheet is at aspeed greater than that, at which the sheet is advanced, so the elementsmooths and calenders the surface of the sheet. The movement of theelement at an angle to the plane of the sheet both compresses the sheetand forces to the surface the amount of water required for satisfactoryealendering.

One form of the new apparatus preferably includes an endless series ofconnected hollow boxes having pervious top surfaces, the series of boxesbeing encircled by a fabric belt. The boxes are supported, so that theseries has a horozintal upper stretch and the boxes in this stretch areevacuated. The belt lies in contact with the tops of the boxes in thestretch and aqueous fibrous cement material is deposited on that portionof the belt. The deposited material is then formed into a sheet, fromwhich excess water is removed by suction applied to the sheet throughthe boxes and belt. The simultaneous calendering and compressingoperations are performed on the fibrous cement sheet after a part of theexcess water has been removed therefrom, and, if desired, the suctionapplied to the portion of the sheet being calendered and compressed maybe reduced or entirely cut off. The belt continues in its plane beyondthe end of the horizontal upper stretch of the series of boxes and theportion of the belt beyond the stretch is maintained in position by asupport. If desired, the calendering and compressing operation may beperformed on the sheet in contact with the belt above the supporttherefor. When the separate support is employed, it is desirable tosubject the belt to a dewatering action between the end of the upperstretch of the series of boxes and the support spaced therefrom. Thisfacilitates the movement of the belt over the support, since anexcessive Water content in the belt has been found to impede itsmovement.

The apparatus of the invention may be used to particular advantage inthe production of thick sheets, which can be dewatered only by intensesuction action. The apparatus may also be employed for other purposesas, for example, for establishing intimate contact between the sheet andgranular material deposited over the surface thereof.

In the new apparatus, a ealendering and compressing element is mountedabove the sheet and operated, so that it has a movement with a componentparallel to the plane of the sheet and another component at an angle tothat plane. It is desirable to mount the element for cyclical movementand, for this purpose, it may be mounted to rotate about the axis of ashaft, which is simultaneously moved toward and away from the suctionsupport. The element is rotated with a surface speed different from thatof the rate of advance of the sheet, in order that calendering actionmay be effected, and, preferably, the shaft is moved toward and awayfrom the plane of the sheet a number of times during each rotation ofthe element about the axis of the shaft. The mounting for the elementand the means for operating it in the manner described may take variousforms, which will be illustrated and described in detail.

For a better understanding of the invention, reference may be made tothe accompanying drawings, in which:

Fig. l is a view in side elevation with parts broken away of one form ofthe new apparatus for practicing the method of the invention;

Fig. 2 is a plan view with parts broken away of the apparatus of Fig. 1;

Fig. 3 is a fragmentary view in side elevation of a modified form of theapparatus;

Fig. 4 is a plan view of the apparatus shown in Fig. 3;

Fig. 5 is a sectional view on an enlarged scale on the line 55 of Fig.1;

Fig. 6 is a sectional view similar to Fig. 5 of a modified form of theapparatus;

Fig. 7 is a sectional view on the line 77 of Fig. 6; and

Fig. 8 is a side elevational view of another form of the apparatus.

The apparatus shown in Fig. l is for use in the production of alongitudinally corrugated asbestos cement sheet of indefinite length,which is subsequently cut into units of the desired size. The apparatuscomprises a framework 11 carrying bearings 12, in which rotate shafts13, at least one of which is driven by a motor 14 through a speedreduction gear box 15. The shafts 13 have wheels 16 fast thereon, and anendless chain of connected ho}- low suction boxes 17 is trained aboutthe wheels, the boxes having a length somewhat greater than the width ofthe sheet to be produced. The outer faces of the boxes are perforatedand the boxes have slots in their under surfaces near their ends, theslots extending in the direction of travel of the chain.

The boxes in the upper horizontal stretch 18 of the chain are supportedfrom beneath by a pair of suction chambers 19 mounted on the framemembers and lying near the ends of the boxes in stretch 18. Each chamberhas a longitudinal slot in its top registering with slots in the bottomsof boxes in the stretch and, in the construction shown, each chamber hasan internal partition 21 subdividing it into two sub-chambers 19a, 19b.The sub-chambers are connected by respective lines 22, 23 to a vacuumpump and line 23 leading to sub-chamber 19b contains a valve 24. Onevacuation of the chambers 19, suction is applied to the boxes throughthe slots 20 in the tops of the chambers and the slots in the bottoms ofthe boxes. The chain of boxes in the lower stretch 25 is supported onrails 26 mounted on cross-beams 27 attached to the framework. In theoperation of the apparatus, the chain of boxes advances in the directionof the arrow, Fig. l.

The chain of boxes is encircled by a belt 28 of waterpervious fabric,which is trained about rollers 29 and has an upper stretch 28a lying incontact with the tops of the boxes in the upper stretch 18 of the chain.Since the sheet produced is to have longitudinal corrugations, the outerperforated surfaces of the boxes are similarly corrugated and the upperstretch of the belt must be formed to fit the tops of the boxes instretch 18. For this purpose, the belt leaving the upper roller 29passes between upper and lower sets of rollers 30, 31 mounted in offsetrelation on respective shafts 32, 33, the shafts lying sufficientlyclose together, so that the belt is folded to longitudinally corrugatedform in passing between the rollers. The boxes in the stretch 18 of thechain and the belt in contact with the tops of the boxes form a suctionsupport, which gives the lower face of the sheet its desired form andalso dewaters the sheet.

Beyond the end of stretch 18 of the chain of boxes, the belt passes overa corrugated fixed support 34, at the end of which is an angle bar 35.The belt turns at right angles around bar 35 to lose contact abruptlywith the under surface of sheet S and, after passing around the lowerrollers 29, the belt is cleaned by a spray nozzle 36. The belt becomesflat on leaving bar 35 and remains fiat until it reaches rollers 30, 31.

The aqueous fibrous cement material is delivered from a source through aflexible hose 37 having a nozzle 38 to a distributing device generallydesignated 39, the device lying above the suction support. The deviceincludes a frame made up of side plates 40, in which are mounted shafts41 provided with flanged wheels 42 running on tracks 43 supported on theframework of the apparatus and lying on opposite sides of the upperstretch of the chain of boxes. Each track has end sections withhorizontal top surfaces and a mid-section having a top surface inclinedupwardly in the direction of travel of the chain of boxes and belt. Theshafts 41 carry corrugated rollers 44 fast thereon, and one shaftcarries a gear 45 engaged by a pinion 46 on the shaft of a motor 47mounted on the frame of the device. The motor is of the reversing typeand, during the operation of the device, it drives one pair of wheels 42alternately in opposite directions, so that the device is reciprocatedlengthwise of the rails 43.

The nozzle 38 extends through a slot in a fixed guide 48 attached to thechambers 19 and extending diagonally across the path of reciprocation ofthe distributing device 39. The nozzle also projects through a slot in aguide 49 mounted on the device and extending at right angles to the pathof reciprocation of the device. As the device reciprocates, the nozzleis moved with it and is caused to reciprocate transversely of the pathof travel of the device by the action of the guides. The fibrous cementmaterial is deposited through the nozzle on the surface of the suctionsupport between the rollers 44 and, as the distributing devicereciprocates, the deposited material is distributed and formed into acorrugated sheet.

Beyond the distributing device, the sheet is preliminarily compressed bya corrugated roller 50 on a shaft 51 in carriage 52. The carriage isprovided with a secand shaft 51a, and the shafts have flanged rollers 53running on tracks 54 with horizontal top surfaces. A motor 55 is mountedon the carriage and a pinion 56 on the motor shaft meshes with a gear 57fast on shaft 51. The motor is of the reversing type and so operatedthat the carriage is reciprocated on tracks 54 during the operation ofthe apparatus. Roller 50 bears on the sheet and compresses it.

A framework 58 supports a motor 59 driving a shaft 60 through a gearreduction box 61. The shaft 60 carries a pair of pulleys 62, 63, whichare connected by respective belts 64, to pulleys 66, 67. Pulley 66 isfast on a shaft 68 having eccentric bushings 69 fast thereon, thebushings rotating in bearings 70 carried by the framework 58. Acorrugated roller 71 is mounted for free rotation on bearings 72 onshaft 68 and pulley 67 encircles shaft 68 and is attached to one end ofthe roller. In the operation of the apparatus, the shaft 68 and theroller 71 are continuously rotated and the roller lies in contact withthe fibrous cement sheet S on top of the suction support. The surfacespeed of the roller is greater than that of the sheet, so that theroller calen-r ders the sheet, and, because of the eccentric bushings 69on the shaft 68, the rotation of the shaft causes the roller to movetoward and away from the sheet and thereby intermittently compress thesheet. The compression of the sheet forces water to the surface of thesheet and such water facilities the calendering action of the roller onthe sheet.

In the form of the apparatus shown in Fig. 1, the roller 71 acts on thesheet lying on the part of the suction support overlying thesub-chambers 19b. During the calendering and compressing action ofroller 71, the sheet is subjected to a degree of suction controlled bythe setting of valve 24. Preferably, the suction applied to the portionof the sheet being compressed and calendered is less intense than thatapplied to the sheet during its formation and preliminary compression,and, if desired, the suction may be wholly cut off from sub-chambers19b.

The modified construction of the calendering and compressing deviceshown in Figs. 3 and 4 is the same as that above described but ismounted in such manner that the corrugated roller 71 corresponding toroller 71 acts on sheet S lying on belt 28 in contact with the fixedsupport 34'. Excess water is removed from the belt by a suction roller73 engaging the under surface of the belt between the end of the suctionsupport and the support 34'.

The modified construction of the calendering and compressing deviceshown in Figs. 6 and 7 includes a shaft 74, on which corrugated roller75 is mounted for free rotation. A pinion 76 fast on the shaft mesheswith a gear 77 fast on a shaft 78 supported in hearings in arms 79pivotally mounted on shaft 74. Shaft 78 also carries a pinion 80 meshingwith a gear 81 loosely encircling shaft 74 and secured to one end ofroller 75. Shaft 74 has eccentric bushings, 82 fast thereon, thebushings being rotatable in fixed bearings 83 carried by supports 84.The arms 79 are connected by links 85 to supports 84. Shaft 74 carries apulley 86 driven by a motor and gear reduction box (not shown) through abelt 87.

The modified calendering and compressing device shown in Fig. 8 includesa corrugated roller 88 acting on sheet S and supported for rotation inthe lower ends of rods 89, the upper ends of which are pivotallysupported on a shaft 90 urged downwardly by compression springs 91acting against a fixed abutment 92. The rods 89 are oscillated byconnecting rods 93 attached to respective crank discs 94. Roller 88 isprovided with a pulley 95 connected by a belt 96 to a pulley 97 on shaft90. Shaft 90 carries another pulley 98 connected by belt 99 to one ofthe crank discs 94. The discs are fast on a shaft carrying a pulley 100connected by a belt 101 to a pulley on the shaft of a motor 102.

In the operation of the apparatus described, the aqueous fibrous cementmaterial is deposited on the suction support within the distributingdevice 39 and the latter: reciprocates lengthwise of the direction. oftravelof the suction support to distribute the material and form it intoa corrugated sheet. The 'sheet is advanced to the preliminarycompressing roller and is then carried along with the support andsubjected to simultaneous calendering and compressing operationsperformed by the roller. As the roller rotates at a higher surface speedthan the sheet, it smooths the latter and the movement of the shaft, onwhich the roller is mounted, causes the roller to compress the sheetintermittently to bring water to the surface thereof to facilitate thecalendering operation.

In the construction shown in Figs. 1 and 2, the sheet may be dewateredby suction applied through sub-chambers 1%, while the calendering andcompressing operations are carried on, and, preferably, the suction soapplied is less than that applied to the sheet elsewhere. In theconstruction shown in Fig. 2, the sheet is supported on the stationarysupport 34', while being simultaneously calendered and compressed, andno dewatering action takes place during these operations.

The calendering and compressing roller 75 in the Fig. 6 constructionfunctions in the same manner as rollers 71, 71 in the constructionsshown in Figs. 1 and 3, in that the axis of shaft 74, on which roller 75rotates, is caused to describe a circle during the rotation of theroller. The roller is, accordingly, moved toward and away from the sheetrepeatedly to subject the latter to compression. In the forms of theapparatus shown in Figs. 1, 3, and 6, the rotational speed of the shaftis preferably much greater than that of the roller, as, for example, theshaft may rotate at 300 R. P. M. and the roller at 30 R. P. M., so thatthe roller moves toward and away from the sheet ten times during eachrotation of the roller. Such repeated compressing operations duringcalendering are preferred.

In the construction shown in Fig. 8, the calendering and compressingroller 88 has a pendulum movement, so that the pressure exerted by it isdistributed over a larger area of the sheet. This facilitates dewateringof the sheet by suction and produces a compact sheet of minimum watercontent.

In the form of the apparatus shown in Figs. 3 and 4, the calendering andcompressing roller 71' acts on the sheet lying on the belt above thestationary support 34 and the sheet is not being subjected to dewateringby suction during the calendering and compressing operations. It will beapparent, that the support 34 may, if desired, be replaced by a suctionroller or by a movable support with or without a suction system.

The apparatus illustrated produces longitudinally corrugated sheets and,accordingly, the distributing, compressing, and calendering andcompressing rollers and the tops of the boxes and of the fixed supportare all corrugated. Also, the belt is shaped to corrugated form, so thatit will lie in extended contact with the tops of the boxes in the upperstretch of the chain. When the apparatus is to be used for producingflat sheets, the surfaces of the several parts of the apparatusmentioned are either fiat or cylindrical and the rollers for shaping thebelt are omitted.

I claim:

1. An apparatus for the manufacture of fibrous cement sheets, whichcomprises an endless continuously movable hollow support having ahorizontal upper stretch, an endless water-pervious belt encircling thesupport and lying in contact with the top of the support in saidstretch, means for depositing aqueous fibrous cement material upon theportion of the belt in contact with the support, means for forming thedeposited material into a sheet, means for moving the support and beltto advance the sheet edgewise, means for dewatering the sheet by suctionapplied through the support and belt, a rotary calendering andcompressing element in contact with the sheet, a shaft supporting theelement for rotation, means for rotating the element, eccentric bushingsencircling: the shaft, bearings supporting the shaft and bushings forrotation, and means for rotating the shaft and bushings.

2. An apparatus for the manufacture of fibrous cement sheets, whichcomprises an endless continuously movable hollow support having ahorizontal upper stretch, an endless water-pervious belt encircling thesupport and lying in contact with the top of the support in saidstretch, means for depositing aqueous fibrous cement material upon theportion of the belt in contact with the support, means for forming thedeposited material into a sheet, means for moving the support and beltto advance the sheet edgewise, means for dewatering the sheet by suctionapplied through the support and belt, a rotary calendering andcompressing element in contact with the sheet, a shaft supporting theelement for rotation, eccentric bushings encircling the shaft, bearingssupporting the shaft and bushings for rotation, means for rotating theshaft and bushings, and driving connections between the shaft andelement.

3. An apparatus for the manufacture of fibrous cement sheets, whichcomprises an endless continuously movable hollow support having ahorizontal upper stretch, an endless water-pervious belt encircling thesupport and lying in contact with the top of the support in saidstretch, means for depositing aqueous fibrous cement material upon theportion of the belt in contact with the support, means for forming thedeposited material into a sheet, means for moving the support and beltto advance the sheet in its plane, means for dewatering the sheet bysuction applied through the sheet and belt, a rotary element forcalendering and compressing the sheet, a shaft, on which the element ismounted for rotation, eccentric bushings encircling the shaft, bearingssupporting the shaft and bushings for rotation, means rotating theelement relative to the shaft with a surface speed greater than that ofthe sheet, and means independent of the elementrotating means forrotating the shaft and bushings.

4. An apparatus for the manufacture of fibrous cement sheets, whichcomprises an endless continuously movable hollow support having ahorizontal upper stretch, an endless water-pervious belt encircling thesupport and lying in contact with the top of the support in saidstretch, means for depositing aqueous fibrous cement material upon theportion of the belt in contact with the support, means for forming thedeposited material into a sheet, means for moving the support and beltto advance the sheet in its plane, means for dewatering the sheet bysuction applied through the sheet and belt, a rotary element forcalendering and compressing the sheet, a shaft, on which the element ismounted for rotation, eccentric bushings encircling the shaft, bearingssupporting the shaft and bushings for rotation, means rotating theelement relative to the shaft with a surface speed greater than that ofthe sheet, and means rotating the shaft and bushings at a higherrotational rate than the rate of rotation of the element.

5. An apparatus for the manufacture of fibrous cement sheets, whichcomprises an endless continuously movable hollow support having ahorizontal upper stretch, an endless water-pervious belt encircling thesupport and lying in contact with the top of the support in saidstretch, means for depositing aqueous fibrous cement material upon theportion of the belt in contact with the support, means for forming thedeposited material into a sheet, means for moving the support and beltto advance the sheet in its plane, means for dewatering the sheet bysuction applied through the sheet and belt, a rotary element forcalendering and compressing the sheet, a shaft, on which the element ismounted for rotation, eccentric bushings encircling the shaft, bearingssupporting the shaft and bushings for rotation, means for rotating theshaft and bushings, and means driven by the shaft and driving theelement at a lower rotational speed than the shaft and at a highersurface speed than the sheet.

(References on following page) References Cited in the file of thispatent UNITED STATES PATENTS McGrath June 14, 1904 Harrison et a1. Ian.5, 1926 Brookby Mar. 18, 1930 Dom et a1 June 18, 1935 Dorn et a1; Aug.13, 1935 Schroder et a1 May 26, 1936 Salvaneschi Sept. 29, 1942 10 8Brbwn May 8, 1945 Bernard et a1 Apr. 11, 1950 FOREIGN PATENTS ItalySept. 18, 1939 Italy Dec. 4, 1939 Italy Apr. 11, 1940 Italy Dec. 10,1940 Great Britain Sept. 1, 1921

1. AN APPARATUS FOR THE MANUFACTURE OF FIBROUS CEMENT SHEETS, WHICHCOMPRISES AN ENDLESS CONTINOUSLY MOVABLE HOLLOW SUPPORT HAVING AHORIZONTAL UPPER STRETCH, AN ENDLESS WATER-PREVIOUS BELT ENCIRCLING THESUPPORT AND LYING IN CONTACT WITH THE TOP OF THE SUPPORT IN SAIDSTRETCH, MEANS FOR DEPOSITING AQUEOUS FIBROUS CEMENT MATERIAL UPON THEPORTION OF THE BELT IN CONTACT WITH THE SUPPORT, MEANS FOR FORMING THEDEPOSITED MATERIAL INTO A SHEET, MEANS FOR MOVING THE SUPPORT AND BELTTO ADVANCE THE SHEET EDGEWISE, MEANS FOR DEWATERING THE SHEET BY SUCTIONAPPLIED THROUGH THE SUPPORT AND BELT, A ROTARY CALENDER-